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re2.cc
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// Copyright 2003-2009 The RE2 Authors. All Rights Reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Regular expression interface RE2.
//
// Originally the PCRE C++ wrapper, but adapted to use
// the new automata-based regular expression engines.
#include "re2/re2.h"
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#ifdef _MSC_VER
#include <intrin.h>
#endif
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#include <atomic>
#include <iterator>
#include <string>
#include <utility>
#include <vector>
#include "absl/base/macros.h"
#include "absl/container/fixed_array.h"
#include "absl/strings/str_format.h"
#include "util/logging.h"
#include "util/strutil.h"
#include "util/utf.h"
#include "re2/prog.h"
#include "re2/regexp.h"
#include "re2/sparse_array.h"
namespace re2 {
// Controls the maximum count permitted by GlobalReplace(); -1 is unlimited.
static int maximum_global_replace_count = -1;
void RE2::FUZZING_ONLY_set_maximum_global_replace_count(int i) {
maximum_global_replace_count = i;
}
// Maximum number of args we can set
static const int kMaxArgs = 16;
static const int kVecSize = 1+kMaxArgs;
const int RE2::Options::kDefaultMaxMem; // initialized in re2.h
RE2::Options::Options(RE2::CannedOptions opt)
: max_mem_(kDefaultMaxMem),
encoding_(opt == RE2::Latin1 ? EncodingLatin1 : EncodingUTF8),
posix_syntax_(opt == RE2::POSIX),
longest_match_(opt == RE2::POSIX),
log_errors_(opt != RE2::Quiet),
literal_(false),
never_nl_(false),
dot_nl_(false),
never_capture_(false),
case_sensitive_(true),
perl_classes_(false),
word_boundary_(false),
one_line_(false) {
}
// Empty objects for use as const references.
// Statically allocating the storage and then
// lazily constructing the objects (in a once
// in RE2::Init()) avoids global constructors
// and the false positives (thanks, Valgrind)
// about memory leaks at program termination.
struct EmptyStorage {
std::string empty_string;
std::map<std::string, int> empty_named_groups;
std::map<int, std::string> empty_group_names;
};
alignas(EmptyStorage) static char empty_storage[sizeof(EmptyStorage)];
static inline std::string* empty_string() {
return &reinterpret_cast<EmptyStorage*>(empty_storage)->empty_string;
}
static inline std::map<std::string, int>* empty_named_groups() {
return &reinterpret_cast<EmptyStorage*>(empty_storage)->empty_named_groups;
}
static inline std::map<int, std::string>* empty_group_names() {
return &reinterpret_cast<EmptyStorage*>(empty_storage)->empty_group_names;
}
// Converts from Regexp error code to RE2 error code.
// Maybe some day they will diverge. In any event, this
// hides the existence of Regexp from RE2 users.
static RE2::ErrorCode RegexpErrorToRE2(re2::RegexpStatusCode code) {
switch (code) {
case re2::kRegexpSuccess:
return RE2::NoError;
case re2::kRegexpInternalError:
return RE2::ErrorInternal;
case re2::kRegexpBadEscape:
return RE2::ErrorBadEscape;
case re2::kRegexpBadCharClass:
return RE2::ErrorBadCharClass;
case re2::kRegexpBadCharRange:
return RE2::ErrorBadCharRange;
case re2::kRegexpMissingBracket:
return RE2::ErrorMissingBracket;
case re2::kRegexpMissingParen:
return RE2::ErrorMissingParen;
case re2::kRegexpUnexpectedParen:
return RE2::ErrorUnexpectedParen;
case re2::kRegexpTrailingBackslash:
return RE2::ErrorTrailingBackslash;
case re2::kRegexpRepeatArgument:
return RE2::ErrorRepeatArgument;
case re2::kRegexpRepeatSize:
return RE2::ErrorRepeatSize;
case re2::kRegexpRepeatOp:
return RE2::ErrorRepeatOp;
case re2::kRegexpBadPerlOp:
return RE2::ErrorBadPerlOp;
case re2::kRegexpBadUTF8:
return RE2::ErrorBadUTF8;
case re2::kRegexpBadNamedCapture:
return RE2::ErrorBadNamedCapture;
}
return RE2::ErrorInternal;
}
static std::string trunc(absl::string_view pattern) {
if (pattern.size() < 100)
return std::string(pattern);
return std::string(pattern.substr(0, 100)) + "...";
}
RE2::RE2(const char* pattern) {
Init(pattern, DefaultOptions);
}
RE2::RE2(const std::string& pattern) {
Init(pattern, DefaultOptions);
}
RE2::RE2(absl::string_view pattern) {
Init(pattern, DefaultOptions);
}
RE2::RE2(absl::string_view pattern, const Options& options) {
Init(pattern, options);
}
int RE2::Options::ParseFlags() const {
int flags = Regexp::ClassNL;
switch (encoding()) {
default:
if (log_errors())
LOG(ERROR) << "Unknown encoding " << encoding();
break;
case RE2::Options::EncodingUTF8:
break;
case RE2::Options::EncodingLatin1:
flags |= Regexp::Latin1;
break;
}
if (!posix_syntax())
flags |= Regexp::LikePerl;
if (literal())
flags |= Regexp::Literal;
if (never_nl())
flags |= Regexp::NeverNL;
if (dot_nl())
flags |= Regexp::DotNL;
if (never_capture())
flags |= Regexp::NeverCapture;
if (!case_sensitive())
flags |= Regexp::FoldCase;
if (perl_classes())
flags |= Regexp::PerlClasses;
if (word_boundary())
flags |= Regexp::PerlB;
if (one_line())
flags |= Regexp::OneLine;
return flags;
}
void RE2::Init(absl::string_view pattern, const Options& options) {
static absl::once_flag empty_once;
absl::call_once(empty_once, []() {
(void) new (empty_storage) EmptyStorage;
});
pattern_ = new std::string(pattern);
options_.Copy(options);
entire_regexp_ = NULL;
suffix_regexp_ = NULL;
error_ = empty_string();
error_arg_ = empty_string();
num_captures_ = -1;
error_code_ = NoError;
longest_match_ = options_.longest_match();
is_one_pass_ = false;
prefix_foldcase_ = false;
prefix_.clear();
prog_ = NULL;
rprog_ = NULL;
named_groups_ = NULL;
group_names_ = NULL;
RegexpStatus status;
entire_regexp_ = Regexp::Parse(
*pattern_,
static_cast<Regexp::ParseFlags>(options_.ParseFlags()),
&status);
if (entire_regexp_ == NULL) {
if (options_.log_errors()) {
LOG(ERROR) << "Error parsing '" << trunc(*pattern_) << "': "
<< status.Text();
}
error_ = new std::string(status.Text());
error_code_ = RegexpErrorToRE2(status.code());
error_arg_ = new std::string(status.error_arg());
return;
}
bool foldcase;
re2::Regexp* suffix;
if (entire_regexp_->RequiredPrefix(&prefix_, &foldcase, &suffix)) {
prefix_foldcase_ = foldcase;
suffix_regexp_ = suffix;
}
else {
suffix_regexp_ = entire_regexp_->Incref();
}
// Two thirds of the memory goes to the forward Prog,
// one third to the reverse prog, because the forward
// Prog has two DFAs but the reverse prog has one.
prog_ = suffix_regexp_->CompileToProg(options_.max_mem()*2/3);
if (prog_ == NULL) {
if (options_.log_errors())
LOG(ERROR) << "Error compiling '" << trunc(*pattern_) << "'";
error_ = new std::string("pattern too large - compile failed");
error_code_ = RE2::ErrorPatternTooLarge;
return;
}
// We used to compute this lazily, but it's used during the
// typical control flow for a match call, so we now compute
// it eagerly, which avoids the overhead of absl::once_flag.
num_captures_ = suffix_regexp_->NumCaptures();
// Could delay this until the first match call that
// cares about submatch information, but the one-pass
// machine's memory gets cut from the DFA memory budget,
// and that is harder to do if the DFA has already
// been built.
is_one_pass_ = prog_->IsOnePass();
}
// Returns rprog_, computing it if needed.
re2::Prog* RE2::ReverseProg() const {
absl::call_once(rprog_once_, [](const RE2* re) {
re->rprog_ =
re->suffix_regexp_->CompileToReverseProg(re->options_.max_mem() / 3);
if (re->rprog_ == NULL) {
if (re->options_.log_errors())
LOG(ERROR) << "Error reverse compiling '" << trunc(*re->pattern_)
<< "'";
// We no longer touch error_ and error_code_ because failing to compile
// the reverse Prog is not a showstopper: falling back to NFA execution
// is fine. More importantly, an RE2 object is supposed to be logically
// immutable: whatever ok() would have returned after Init() completed,
// it should continue to return that no matter what ReverseProg() does.
}
}, this);
return rprog_;
}
RE2::~RE2() {
if (group_names_ != empty_group_names())
delete group_names_;
if (named_groups_ != empty_named_groups())
delete named_groups_;
delete rprog_;
delete prog_;
if (error_arg_ != empty_string())
delete error_arg_;
if (error_ != empty_string())
delete error_;
if (suffix_regexp_)
suffix_regexp_->Decref();
if (entire_regexp_)
entire_regexp_->Decref();
delete pattern_;
}
int RE2::ProgramSize() const {
if (prog_ == NULL)
return -1;
return prog_->size();
}
int RE2::ReverseProgramSize() const {
if (prog_ == NULL)
return -1;
Prog* prog = ReverseProg();
if (prog == NULL)
return -1;
return prog->size();
}
// Finds the most significant non-zero bit in n.
static int FindMSBSet(uint32_t n) {
DCHECK_NE(n, 0);
#if defined(__GNUC__)
return 31 ^ __builtin_clz(n);
#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_IX86))
unsigned long c;
_BitScanReverse(&c, n);
return static_cast<int>(c);
#else
int c = 0;
for (int shift = 1 << 4; shift != 0; shift >>= 1) {
uint32_t word = n >> shift;
if (word != 0) {
n = word;
c += shift;
}
}
return c;
#endif
}
static int Fanout(Prog* prog, std::vector<int>* histogram) {
SparseArray<int> fanout(prog->size());
prog->Fanout(&fanout);
int data[32] = {};
int size = 0;
for (SparseArray<int>::iterator i = fanout.begin(); i != fanout.end(); ++i) {
if (i->value() == 0)
continue;
uint32_t value = i->value();
int bucket = FindMSBSet(value);
bucket += value & (value-1) ? 1 : 0;
++data[bucket];
size = std::max(size, bucket+1);
}
if (histogram != NULL)
histogram->assign(data, data+size);
return size-1;
}
int RE2::ProgramFanout(std::vector<int>* histogram) const {
if (prog_ == NULL)
return -1;
return Fanout(prog_, histogram);
}
int RE2::ReverseProgramFanout(std::vector<int>* histogram) const {
if (prog_ == NULL)
return -1;
Prog* prog = ReverseProg();
if (prog == NULL)
return -1;
return Fanout(prog, histogram);
}
// Returns named_groups_, computing it if needed.
const std::map<std::string, int>& RE2::NamedCapturingGroups() const {
absl::call_once(named_groups_once_, [](const RE2* re) {
if (re->suffix_regexp_ != NULL)
re->named_groups_ = re->suffix_regexp_->NamedCaptures();
if (re->named_groups_ == NULL)
re->named_groups_ = empty_named_groups();
}, this);
return *named_groups_;
}
// Returns group_names_, computing it if needed.
const std::map<int, std::string>& RE2::CapturingGroupNames() const {
absl::call_once(group_names_once_, [](const RE2* re) {
if (re->suffix_regexp_ != NULL)
re->group_names_ = re->suffix_regexp_->CaptureNames();
if (re->group_names_ == NULL)
re->group_names_ = empty_group_names();
}, this);
return *group_names_;
}
/***** Convenience interfaces *****/
bool RE2::FullMatchN(absl::string_view text, const RE2& re,
const Arg* const args[], int n) {
return re.DoMatch(text, ANCHOR_BOTH, NULL, args, n);
}
bool RE2::PartialMatchN(absl::string_view text, const RE2& re,
const Arg* const args[], int n) {
return re.DoMatch(text, UNANCHORED, NULL, args, n);
}
bool RE2::ConsumeN(absl::string_view* input, const RE2& re,
const Arg* const args[], int n) {
size_t consumed;
if (re.DoMatch(*input, ANCHOR_START, &consumed, args, n)) {
input->remove_prefix(consumed);
return true;
} else {
return false;
}
}
bool RE2::FindAndConsumeN(absl::string_view* input, const RE2& re,
const Arg* const args[], int n) {
size_t consumed;
if (re.DoMatch(*input, UNANCHORED, &consumed, args, n)) {
input->remove_prefix(consumed);
return true;
} else {
return false;
}
}
bool RE2::Replace(std::string* str,
const RE2& re,
absl::string_view rewrite) {
absl::string_view vec[kVecSize];
int nvec = 1 + MaxSubmatch(rewrite);
if (nvec > 1 + re.NumberOfCapturingGroups())
return false;
if (nvec > static_cast<int>(ABSL_ARRAYSIZE(vec)))
return false;
if (!re.Match(*str, 0, str->size(), UNANCHORED, vec, nvec))
return false;
std::string s;
if (!re.Rewrite(&s, rewrite, vec, nvec))
return false;
assert(vec[0].data() >= str->data());
assert(vec[0].data() + vec[0].size() <= str->data() + str->size());
str->replace(vec[0].data() - str->data(), vec[0].size(), s);
return true;
}
int RE2::GlobalReplace(std::string* str,
const RE2& re,
absl::string_view rewrite) {
absl::string_view vec[kVecSize];
int nvec = 1 + MaxSubmatch(rewrite);
if (nvec > 1 + re.NumberOfCapturingGroups())
return false;
if (nvec > static_cast<int>(ABSL_ARRAYSIZE(vec)))
return false;
const char* p = str->data();
const char* ep = p + str->size();
const char* lastend = NULL;
std::string out;
int count = 0;
while (p <= ep) {
if (maximum_global_replace_count != -1 &&
count >= maximum_global_replace_count)
break;
if (!re.Match(*str, static_cast<size_t>(p - str->data()),
str->size(), UNANCHORED, vec, nvec))
break;
if (p < vec[0].data())
out.append(p, vec[0].data() - p);
if (vec[0].data() == lastend && vec[0].empty()) {
// Disallow empty match at end of last match: skip ahead.
//
// fullrune() takes int, not ptrdiff_t. However, it just looks
// at the leading byte and treats any length >= 4 the same.
if (re.options().encoding() == RE2::Options::EncodingUTF8 &&
fullrune(p, static_cast<int>(std::min(ptrdiff_t{4}, ep - p)))) {
// re is in UTF-8 mode and there is enough left of str
// to allow us to advance by up to UTFmax bytes.
Rune r;
int n = chartorune(&r, p);
// Some copies of chartorune have a bug that accepts
// encodings of values in (10FFFF, 1FFFFF] as valid.
if (r > Runemax) {
n = 1;
r = Runeerror;
}
if (!(n == 1 && r == Runeerror)) { // no decoding error
out.append(p, n);
p += n;
continue;
}
}
// Most likely, re is in Latin-1 mode. If it is in UTF-8 mode,
// we fell through from above and the GIGO principle applies.
if (p < ep)
out.append(p, 1);
p++;
continue;
}
re.Rewrite(&out, rewrite, vec, nvec);
p = vec[0].data() + vec[0].size();
lastend = p;
count++;
}
if (count == 0)
return 0;
if (p < ep)
out.append(p, ep - p);
using std::swap;
swap(out, *str);
return count;
}
bool RE2::Extract(absl::string_view text,
const RE2& re,
absl::string_view rewrite,
std::string* out) {
absl::string_view vec[kVecSize];
int nvec = 1 + MaxSubmatch(rewrite);
if (nvec > 1 + re.NumberOfCapturingGroups())
return false;
if (nvec > static_cast<int>(ABSL_ARRAYSIZE(vec)))
return false;
if (!re.Match(text, 0, text.size(), UNANCHORED, vec, nvec))
return false;
out->clear();
return re.Rewrite(out, rewrite, vec, nvec);
}
std::string RE2::QuoteMeta(absl::string_view unquoted) {
std::string result;
result.reserve(unquoted.size() << 1);
// Escape any ascii character not in [A-Za-z_0-9].
//
// Note that it's legal to escape a character even if it has no
// special meaning in a regular expression -- so this function does
// that. (This also makes it identical to the perl function of the
// same name except for the null-character special case;
// see `perldoc -f quotemeta`.)
for (size_t ii = 0; ii < unquoted.size(); ++ii) {
// Note that using 'isalnum' here raises the benchmark time from
// 32ns to 58ns:
if ((unquoted[ii] < 'a' || unquoted[ii] > 'z') &&
(unquoted[ii] < 'A' || unquoted[ii] > 'Z') &&
(unquoted[ii] < '0' || unquoted[ii] > '9') &&
unquoted[ii] != '_' &&
// If this is the part of a UTF8 or Latin1 character, we need
// to copy this byte without escaping. Experimentally this is
// what works correctly with the regexp library.
!(unquoted[ii] & 128)) {
if (unquoted[ii] == '\0') { // Special handling for null chars.
// Note that this special handling is not strictly required for RE2,
// but this quoting is required for other regexp libraries such as
// PCRE.
// Can't use "\\0" since the next character might be a digit.
result += "\\x00";
continue;
}
result += '\\';
}
result += unquoted[ii];
}
return result;
}
bool RE2::PossibleMatchRange(std::string* min, std::string* max,
int maxlen) const {
if (prog_ == NULL)
return false;
int n = static_cast<int>(prefix_.size());
if (n > maxlen)
n = maxlen;
// Determine initial min max from prefix_ literal.
*min = prefix_.substr(0, n);
*max = prefix_.substr(0, n);
if (prefix_foldcase_) {
// prefix is ASCII lowercase; change *min to uppercase.
for (int i = 0; i < n; i++) {
char& c = (*min)[i];
if ('a' <= c && c <= 'z')
c += 'A' - 'a';
}
}
// Add to prefix min max using PossibleMatchRange on regexp.
std::string dmin, dmax;
maxlen -= n;
if (maxlen > 0 && prog_->PossibleMatchRange(&dmin, &dmax, maxlen)) {
min->append(dmin);
max->append(dmax);
} else if (!max->empty()) {
// prog_->PossibleMatchRange has failed us,
// but we still have useful information from prefix_.
// Round up *max to allow any possible suffix.
PrefixSuccessor(max);
} else {
// Nothing useful.
*min = "";
*max = "";
return false;
}
return true;
}
// Avoid possible locale nonsense in standard strcasecmp.
// The string a is known to be all lowercase.
static int ascii_strcasecmp(const char* a, const char* b, size_t len) {
const char* ae = a + len;
for (; a < ae; a++, b++) {
uint8_t x = *a;
uint8_t y = *b;
if ('A' <= y && y <= 'Z')
y += 'a' - 'A';
if (x != y)
return x - y;
}
return 0;
}
/***** Actual matching and rewriting code *****/
bool RE2::Match(absl::string_view text,
size_t startpos,
size_t endpos,
Anchor re_anchor,
absl::string_view* submatch,
int nsubmatch) const {
if (!ok()) {
if (options_.log_errors())
LOG(ERROR) << "Invalid RE2: " << *error_;
return false;
}
if (startpos > endpos || endpos > text.size()) {
if (options_.log_errors())
LOG(ERROR) << "RE2: invalid startpos, endpos pair. ["
<< "startpos: " << startpos << ", "
<< "endpos: " << endpos << ", "
<< "text size: " << text.size() << "]";
return false;
}
absl::string_view subtext = text;
subtext.remove_prefix(startpos);
subtext.remove_suffix(text.size() - endpos);
// Use DFAs to find exact location of match, filter out non-matches.
// Don't ask for the location if we won't use it.
// SearchDFA can do extra optimizations in that case.
absl::string_view match;
absl::string_view* matchp = &match;
if (nsubmatch == 0)
matchp = NULL;
int ncap = 1 + NumberOfCapturingGroups();
if (ncap > nsubmatch)
ncap = nsubmatch;
// If the regexp is anchored explicitly, must not be in middle of text.
if (prog_->anchor_start() && startpos != 0)
return false;
if (prog_->anchor_end() && endpos != text.size())
return false;
// If the regexp is anchored explicitly, update re_anchor
// so that we can potentially fall into a faster case below.
if (prog_->anchor_start() && prog_->anchor_end())
re_anchor = ANCHOR_BOTH;
else if (prog_->anchor_start() && re_anchor != ANCHOR_BOTH)
re_anchor = ANCHOR_START;
// Check for the required prefix, if any.
size_t prefixlen = 0;
if (!prefix_.empty()) {
if (startpos != 0)
return false;
prefixlen = prefix_.size();
if (prefixlen > subtext.size())
return false;
if (prefix_foldcase_) {
if (ascii_strcasecmp(&prefix_[0], subtext.data(), prefixlen) != 0)
return false;
} else {
if (memcmp(&prefix_[0], subtext.data(), prefixlen) != 0)
return false;
}
subtext.remove_prefix(prefixlen);
// If there is a required prefix, the anchor must be at least ANCHOR_START.
if (re_anchor != ANCHOR_BOTH)
re_anchor = ANCHOR_START;
}
Prog::Anchor anchor = Prog::kUnanchored;
Prog::MatchKind kind =
longest_match_ ? Prog::kLongestMatch : Prog::kFirstMatch;
bool can_one_pass = is_one_pass_ && ncap <= Prog::kMaxOnePassCapture;
bool can_bit_state = prog_->CanBitState();
size_t bit_state_text_max_size = prog_->bit_state_text_max_size();
#ifdef RE2_HAVE_THREAD_LOCAL
hooks::context = this;
#endif
bool dfa_failed = false;
bool skipped_test = false;
switch (re_anchor) {
default:
LOG(DFATAL) << "Unexpected re_anchor value: " << re_anchor;
return false;
case UNANCHORED: {
if (prog_->anchor_end()) {
// This is a very special case: we don't need the forward DFA because
// we already know where the match must end! Instead, the reverse DFA
// can say whether there is a match and (optionally) where it starts.
Prog* prog = ReverseProg();
if (prog == NULL) {
// Fall back to NFA below.
skipped_test = true;
break;
}
if (!prog->SearchDFA(subtext, text, Prog::kAnchored,
Prog::kLongestMatch, matchp, &dfa_failed, NULL)) {
if (dfa_failed) {
if (options_.log_errors())
LOG(ERROR) << "DFA out of memory: "
<< "pattern length " << pattern_->size() << ", "
<< "program size " << prog->size() << ", "
<< "list count " << prog->list_count() << ", "
<< "bytemap range " << prog->bytemap_range();
// Fall back to NFA below.
skipped_test = true;
break;
}
return false;
}
if (matchp == NULL) // Matched. Don't care where.
return true;
break;
}
if (!prog_->SearchDFA(subtext, text, anchor, kind,
matchp, &dfa_failed, NULL)) {
if (dfa_failed) {
if (options_.log_errors())
LOG(ERROR) << "DFA out of memory: "
<< "pattern length " << pattern_->size() << ", "
<< "program size " << prog_->size() << ", "
<< "list count " << prog_->list_count() << ", "
<< "bytemap range " << prog_->bytemap_range();
// Fall back to NFA below.
skipped_test = true;
break;
}
return false;
}
if (matchp == NULL) // Matched. Don't care where.
return true;
// SearchDFA set match.end() but didn't know where the
// match started. Run the regexp backward from match.end()
// to find the longest possible match -- that's where it started.
Prog* prog = ReverseProg();
if (prog == NULL) {
// Fall back to NFA below.
skipped_test = true;
break;
}
if (!prog->SearchDFA(match, text, Prog::kAnchored,
Prog::kLongestMatch, &match, &dfa_failed, NULL)) {
if (dfa_failed) {
if (options_.log_errors())
LOG(ERROR) << "DFA out of memory: "
<< "pattern length " << pattern_->size() << ", "
<< "program size " << prog->size() << ", "
<< "list count " << prog->list_count() << ", "
<< "bytemap range " << prog->bytemap_range();
// Fall back to NFA below.
skipped_test = true;
break;
}
if (options_.log_errors())
LOG(ERROR) << "SearchDFA inconsistency";
return false;
}
break;
}
case ANCHOR_BOTH:
case ANCHOR_START:
if (re_anchor == ANCHOR_BOTH)
kind = Prog::kFullMatch;
anchor = Prog::kAnchored;
// If only a small amount of text and need submatch
// information anyway and we're going to use OnePass or BitState
// to get it, we might as well not even bother with the DFA:
// OnePass or BitState will be fast enough.
// On tiny texts, OnePass outruns even the DFA, and
// it doesn't have the shared state and occasional mutex that
// the DFA does.
if (can_one_pass && text.size() <= 4096 &&
(ncap > 1 || text.size() <= 16)) {
skipped_test = true;
break;
}
if (can_bit_state && text.size() <= bit_state_text_max_size &&
ncap > 1) {
skipped_test = true;
break;
}
if (!prog_->SearchDFA(subtext, text, anchor, kind,
&match, &dfa_failed, NULL)) {
if (dfa_failed) {
if (options_.log_errors())
LOG(ERROR) << "DFA out of memory: "
<< "pattern length " << pattern_->size() << ", "
<< "program size " << prog_->size() << ", "
<< "list count " << prog_->list_count() << ", "
<< "bytemap range " << prog_->bytemap_range();
// Fall back to NFA below.
skipped_test = true;
break;
}
return false;
}
break;
}
if (!skipped_test && ncap <= 1) {
// We know exactly where it matches. That's enough.
if (ncap == 1)
submatch[0] = match;
} else {
absl::string_view subtext1;
if (skipped_test) {
// DFA ran out of memory or was skipped:
// need to search in entire original text.
subtext1 = subtext;
} else {
// DFA found the exact match location:
// let NFA run an anchored, full match search
// to find submatch locations.
subtext1 = match;
anchor = Prog::kAnchored;
kind = Prog::kFullMatch;
}
if (can_one_pass && anchor != Prog::kUnanchored) {
if (!prog_->SearchOnePass(subtext1, text, anchor, kind, submatch, ncap)) {
if (!skipped_test && options_.log_errors())
LOG(ERROR) << "SearchOnePass inconsistency";
return false;
}
} else if (can_bit_state && subtext1.size() <= bit_state_text_max_size) {
if (!prog_->SearchBitState(subtext1, text, anchor,
kind, submatch, ncap)) {
if (!skipped_test && options_.log_errors())
LOG(ERROR) << "SearchBitState inconsistency";
return false;
}
} else {
if (!prog_->SearchNFA(subtext1, text, anchor, kind, submatch, ncap)) {
if (!skipped_test && options_.log_errors())
LOG(ERROR) << "SearchNFA inconsistency";
return false;
}
}
}
// Adjust overall match for required prefix that we stripped off.
if (prefixlen > 0 && nsubmatch > 0)
submatch[0] = absl::string_view(submatch[0].data() - prefixlen,
submatch[0].size() + prefixlen);
// Zero submatches that don't exist in the regexp.
for (int i = ncap; i < nsubmatch; i++)
submatch[i] = absl::string_view();
return true;
}
// Internal matcher - like Match() but takes Args not string_views.
bool RE2::DoMatch(absl::string_view text,
Anchor re_anchor,
size_t* consumed,
const Arg* const* args,
int n) const {
if (!ok()) {
if (options_.log_errors())
LOG(ERROR) << "Invalid RE2: " << *error_;
return false;
}
if (NumberOfCapturingGroups() < n) {
// RE has fewer capturing groups than number of Arg pointers passed in.
return false;
}
// Count number of capture groups needed.
int nvec;
if (n == 0 && consumed == NULL)
nvec = 0;
else
nvec = n+1;
absl::FixedArray<absl::string_view, kVecSize> vec_storage(nvec);
absl::string_view* vec = vec_storage.data();
if (!Match(text, 0, text.size(), re_anchor, vec, nvec)) {
return false;
}
if (consumed != NULL)
*consumed = static_cast<size_t>(EndPtr(vec[0]) - BeginPtr(text));
if (n == 0 || args == NULL) {
// We are not interested in results
return true;
}
// If we got here, we must have matched the whole pattern.
for (int i = 0; i < n; i++) {
absl::string_view s = vec[i+1];
if (!args[i]->Parse(s.data(), s.size())) {
// TODO: Should we indicate what the error was?
return false;
}
}
return true;
}
// Checks that the rewrite string is well-formed with respect to this
// regular expression.
bool RE2::CheckRewriteString(absl::string_view rewrite,
std::string* error) const {
int max_token = -1;
for (const char *s = rewrite.data(), *end = s + rewrite.size();
s < end; s++) {
int c = *s;
if (c != '\\') {
continue;
}
if (++s == end) {
*error = "Rewrite schema error: '\\' not allowed at end.";
return false;
}
c = *s;
if (c == '\\') {
continue;
}
if (!isdigit(c)) {
*error = "Rewrite schema error: "
"'\\' must be followed by a digit or '\\'.";
return false;
}
int n = (c - '0');
if (max_token < n) {
max_token = n;
}
}
if (max_token > NumberOfCapturingGroups()) {
*error = absl::StrFormat(
"Rewrite schema requests %d matches, but the regexp only has %d "
"parenthesized subexpressions.",
max_token, NumberOfCapturingGroups());
return false;
}
return true;
}
// Returns the maximum submatch needed for the rewrite to be done by Replace().
// E.g. if rewrite == "foo \\2,\\1", returns 2.